Light emitting device and adaptive driving beam headlamp system

ABSTRACT

A light emitting device includes a substrate, a plurality of first wiring members, a plurality of second wiring members and a plurality of light emitting elements. The first wiring members extend in a first direction. The second wiring members extend in a second direction. Each of the second wiring members is segmented into a plurality of second wiring portions. The light emitting elements are disposed along the second direction. A first electrode of the light emitting element is connected to a corresponding one of the first wiring members. A second electrode of the light emitting element has a first connection part and a second connection part that is linked to the first connection part. The first connection part and the second connection part are connected to a corresponding one of the second wiring members and bridge at least two of the segmented second wiring portions in the second direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.14/924,831 filed on Oct. 28, 2015, now U.S. Pat. No. 9,722,160. Thisapplication claims priority to Japanese Patent Application No.2014-222249 filed on Oct. 31, 2014, and No. 2015-187821 filed on Sep.25, 2015. The entire disclosures of U.S. patent application Ser. No.14/924,831, Japanese Patent Application No. 2014-222249 and No.2015-187821 are hereby incorporated herein by reference.

BACKGROUND 1. Technical Field

The present disclosure relates to a light emitting device and to anadaptive driving beam headlamp system.

2. Description of Related Art

With a light emitting device featuring light emitting diodes (LEDs) orother such light emitting elements, a plurality of light emittingelements are mounted on an insulated substrate on which matrix wiringhas been formed. As a result, high brightness is obtained, and suchdevices have been utilized as automotive light sources and the like inrecent years.

However, in the case of forming a matrix wiring on a substrate,particularly in order to individually turn on and off each of aplurality of light emitting elements, usually, a multilayer wiring isrequired, resulting in a complicated configuration, which requirescomplex manufacturing process and higher manufacturing costs. Also, thisresults in an increase in the size of the substrate, obstructing theminiaturization of the light emitting device.

The product of clamping, affixing, or otherwise attaching a thin-filmwiring pattern to a green sheet of aluminum oxide or another suchceramic and then firing has been used in the past as a multilayer wiringor inner layer wiring board, for example, JP2009-135535A. However, witha light source in which high-density mounting is required in order toachieve high brightness, such as with an automotive light source, thewidth, pitch, and so forth of the wiring pattern need to bemicrominiaturized, and a decrease in the dimensional accuracy of awiring pattern caused by shrinkage accompanying the firing of a ceramicmakes it difficult to design the wiring of a matrix board.

Also, while various kinds of matrix wiring have been proposed for lightemitting devices, for example, JP2009-302542A, a light emitting deviceneeds to be designed that corresponds to the wiring pattern of thewiring board in order to adequately ensure the performance of theindividual light emitting elements.

SUMMARY

An object of the present disclosure is to provide a light emittingdevice and an adaptive driving beam headlamp system with whichindividual turning on and off is possible, while the performance of thelight emitting elements can be fully realized.

A light emitting device of the present disclosure includes: a substratehaving a first main surface; a plurality of first wiring that are formedon the first main surface and extend in a first direction; a pluralityof second wiring that are formed on the first main surface, extend in asecond direction, and are segmented in each second wiring; and aplurality of light emitting elements equipped with a first electrode anda second electrode disposed on the same face side of a semiconductorstacked-layer structure. The plurality of light emitting elements aredisposed along the second direction, the first electrode is connectedopposite the first wiring, the second electrode has a first connectionpart and a second connection part that is linked to the first connectionpart. The first connection part and the second connection part areconnected opposite the second wiring and bridging at least two of thesegmented second wiring in the second direction.

Further, an adaptive driving beam headlamp system includes theabove-mentioned light emitting device; an on-board camera thatrecognizes the position of a vehicle ahead; and an electronic controlunit that determines the light distribution pattern and the area to beshaded.

The present disclosure can provide a light emitting device with which asmaller size is achieved with a simple structure, and individual turningon and off is possible while achieving sufficient performance of thelight emitting elements.

Furthermore, this light emitting device can be used to provide ahigh-performance adaptive driving beam headlamp system.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a simplified plan view of a drive substrate in an embodimentof the light emitting device disclosed herein;

FIG. 1B is a simplified plan view of the drive substrate in FIG. 1A inwhich light emitting elements have been mounted;

FIG. 1C is a simplified plan view of a light emitting element, showingthe layout of the electrodes of the light emitting elements installed onthe drive substrate in FIG. 1A;

FIG. 1D is a simplified plan view of a light emitting element, showinganother layout of the electrodes of the light emitting elementsinstalled on the drive substrate in FIG. 1A;

FIG. 1E is a cross section along the A-A′ line in FIG. 1D;

FIG. 1F is a cross section along the B-B′ line in FIG. 1D;

FIG. 1G is a diagram of a matrix circuit involving a drive substrate inwhich light emitting elements have been installed;

FIG. 2A is a simplified cross section (cut along the A-A′ line in FIG.1A) of the manufacturing steps for the light emitting device disclosedherein;

FIG. 2B is a simplified cross section of the manufacturing steps for thelight emitting device according to an embodiment of the presentinvention;

FIG. 2C is a simplified cross section of the manufacturing steps for thelight emitting device according to an embodiment of the presentinvention;

FIG. 2D is a simplified plan view of the light emitting device of FIG.2C;

FIG. 3A is a simplified plan view showing an example of the drivesubstrate according to an embodiment of the present invention;

FIG. 3B is a simplified plan view of the drive substrate in FIG. 3A inwhich light emitting elements have been installed;

FIG. 4A is a simplified plan view showing an example of the drivesubstrate according to an embodiment of the present invention;

FIG. 4B is a simplified plan view of the drive substrate in FIG. 4A inwhich light emitting elements have been installed;

FIG. 4C is a simplified plan view of a light emitting element, showingthe layout of the electrodes of the light emitting elements installed onthe drive substrate in FIG. 4A;

FIG. 5A is a simplified plan view showing an example of the drivesubstrate according to an embodiment of the present invention;

FIG. 5B is a simplified plan view of the drive substrate in FIG. 5A inwhich light emitting elements have been installed;

FIG. 6A is a block diagram of the electrical configuration of theadaptive driving beam headlamp system according to an embodiment of thepresent invention; and

FIG. 6B is a flowchart of the control flow in the adaptive driving beamheadlamp system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The sizes and the arrangement relationships of the members in each ofdrawings are occasionally shown exaggerated for ease of explanation.Further, in the description below, the same designations or the samereference numerals may, in principle, denote the same or like membersand duplicative descriptions will be appropriately omitted.

Light Emitting Device

The light emitting device of this embodiment has a drive substrate thatincludes a substrate having a first main surface, a plurality of firstwiring that extend in a first direction, and a plurality of secondwiring that are formed on the first main surface, extend in a seconddirection, and are segmented in their layout, as well as a plurality oflight emitting elements that are mounted on this drive substrate and areequipped with a first electrode and a second electrode disposed on thesame face side of a semiconductor stacked-layer structure.

Drive Substrate Substrate

The substrate has a first main surface. Preferably, the substrate alsohas a second main surface as a main surface on the opposite side fromthe first main surface. The first main surface and/or the second mainsurface is preferably flat. The shape of the substrate is preferablythat of a rectangular flat board, for example.

The thickness and size of the substrate can be suitably adjustedaccording to the size, number, and so forth of the light emittingelements to be mounted. For instance, the thickness of the substrate maybe about 0.05 to 10 mm, with about 0.1 to 1 mm being preferable. Anexample of the size is from about 50×50 mm to 100×100 mm.

The substrate may be formed from a material with insulating properties,examples thereof include alumina, aluminum nitride and other suchceramic substrates, glass substrates, glass epoxy substrates, paperphenol substrates, paper epoxy substrates, glass composite substrates,low-temperature co-fired ceramic (LTCC) substrates, thermoplastic resin,thermosetting resin and other such resin substrates. Of these, a ceramicsubstrate is preferable, and a substrate composed of aluminum nitride ismore preferable from the standpoint of heat dissipation. Also, thethermal conductivity is preferably at least 170 W/m·K.

The substrate preferably has a single-layer structure, and a ceramicsubstrate with a single-layer structure is particularly preferable.However, in the manufacturing process, two or more layers may be stackedand finally integrated to produce the substrate.

When a ceramic substrate is used, it may be manufactured by a co-firingmethod, but a post-firing method is preferable in order to obtain asubstrate with better dimensional accuracy. Post-firing is a method inwhich wiring is formed on a ceramic board that has already been fired.When wiring is formed by post-firing, a fine pattern can be formed byplating, sputtering, vacuum vapor deposition, or the like involvinglift-off with a mask pattern, by a photolithographic technique.

First Wiring and Second Wiring

The first and second wiring are formed on the first main surface of thesubstrate.

The first and second wiring are, for example, electrically connected tothe light emitting elements and an external power source, and are usedto apply voltage from the external power source to the light emittingelements. As will be discussed below, the first wiring are connected tothe first electrodes of the light emitting elements, and the secondwiring are connected to the second electrodes of the light emittingelements. The first wiring and the second wiring may correspond toeither an anode or a cathode, but the first wiring preferably correspondto cathode, and the second wiring to anode.

There are a plurality of independent first wiring disposed extending inthe first direction on the first main surface of the substrate. The“first direction” here may be any direction, but can be, for example, adirection corresponding to the x axis in two dimensions (such as the rowdirection). The concept of extending in the first electrode is notlimited to extending linearly (such as 11 in FIGS. 1A and 21 in FIG.3A), and also encompasses extending toward the first direction in astepped shape (41 in FIG. 5A), a curved shape, or a combination thereof.As long as single first wiring extends in the first direction, the firstwiring may be partially branched (branching in two, in three (31 in FIG.4A), etc.), or may have a part that is partially branched. The branchedfirst wiring are preferably adjacent to each other and extendsubstantially in parallel.

The second wiring extend in the second direction on the first mainsurface of the substrate, and are segmented in to a plurality of secondwiring portions (such as 22 x . . . in FIG. 3A), and a plurality ofthese second wiring are preferably disposed independently from eachother (such as 22 x, 22 y, and 22 z in FIG. 3A, 32 x, 32 y, and 32 z inFIG. 4A, and 42 x, 42 y, and 42 z in FIG. 5A). The second direction heremay be any direction as long as it intersects the first wiring extendingin the first direction. The angle of this intersection preferably be aperpendicular direction (such as the column direction, corresponding tothe y axis). However, the term perpendicular here means that variance ofabout ±10° is permissible. Also, the concept of being disposed along thesecond direction is not limited to being disposed on a straight line,and also encompasses being disposed on a line that is stepped, curved,or a combination of these shapes when such a line extends toward thesecond direction.

The term “a plurality of” here means that a plurality of second wiringare disposed so as to make pairs with the plurality of first wiring.Also, when the second wiring extend along the second direction, theywill usually intersect the first wiring at one or more places, but atthe places corresponding to these intersection points, the second wiringare disposed not intersecting with the first wiring, but separated fromthe first wiring. In other words, since the second wiring are segmentedand disposed at the locations corresponding to the sites of intersectionwith the first wiring, this can also mean that a single second wiringthat forms a pair with a single first wiring is constituted by aplurality of segmented pieces (segmented second wiring portions). Aslong as a single second wiring is disposed along the second direction,the second wirings may be disposed in parallel and adjacent to eachother so as to correspond to branching in two (12 in FIG. 1A), branchingin three, etc. There may also be parts that are partially branched.

The outer peripheries of the first wiring and the second wiring arepreferably arranged in a regular pattern in the column and rowdirections so as to create a square shape, rectangular shape, diamondshape, or the like, for example.

The first and second wiring can be formed from a material that conductselectricity, such as a single-layer film or stacked film of gold (Au),silver (Ag), copper (Cu), tungsten (W), nickel (Ni) or another suchmetal or alloy. The thickness of the first and second wiring may eachhave the same thickness overall, or may be partially different in theirthickness. The total thickness of the first wiring and the second wiringis about 1 to 100 μm, for example.

In the case of forming the first wiring and/or the second wiring with astacked film, the first wiring and/or the second wiring may havepartially different structures in a direction of thickness or in-plane.For example, part of the surface of the first wiring or the secondwiring is remover by laser trimming, and an exposed surface of the firstwiring or the second wiring thus obtained may be converted to the oxide.More specifically, in the case where the first wiring or the secondwiring is formed with a stacked structure of TiW/Cu/Ni/Au, the Au may beremoved by laser trimming to expose the Ni, and the exposed surface ofthe Ni may be oxidized.

The width and spacing of the first and second wiring can be suitablyadjusted according to the size, number, density, brightness, and soforth of the light emitting elements that are mounted on the drivesubstrate to be obtained. For instance, the width of the first wiring ispreferably about at least one fifth to less than one half the length ofone side of a light emitting element. In case where two or more firstwiring are arranged for each light emitting element, their combinedwidth may be about within this range. The width of the second wiring ispreferably more than one fifth and no more than about one half thelength of one side of a light emitting element. In case where two ormore second wiring are arranged for each light emitting element, theircombined width may be about within this range. It is particularlypreferred for the second wiring to be wider than the first wiring. Theterm “wider” here means that the length of the second wiring in thefirst direction (M in FIG. 1A), or, in case where the second wiring isbranched, the combined width of the branches (N1+N2 in FIG. 1A), isgreater than the length of the first wiring in the second direction (Qin FIG. 1A). This also means that in case where the first wiring isbranched, the width of the second wiring (M in FIG. 4A) is greater thanthe combined length of the branches of the first wirings in the seconddirection (P1+P2+P3 in FIG. 4A).

Thus making the second wiring wider than the first wiring allows theheat produced in the light emitting layer during emission to beeffectively released by the wider second wiring. That is, the region inthe light emitting element (discussed below) in which there is a secondconduction layer connected via a second electrode is the region in whichthe light emitting layer is present, and heat is generated there duringemission. Thus, when this heat is released first by the secondconduction layer, then by the second electrode, and then by the secondwiring, it can be dissipated more effectively if the second wiring iswider.

The first wiring and the second wiring are disposed separated from eachother on the first main surface of the substrate. In other words, theyare not disposed three-dimensionally, and instead are preferably formedby the same layer. Therefore, the two are preferably formed from thesame metal material, that is, by a single layer or a stacked layer ofthe same metal or alloy. For example, they are preferably formed at thesame time by metal layers of the same composition using a mask pattern.

The first main surface of the substrate may further include padelectrodes for connecting to electronic parts such as connectors,routing wirings for leading the above-mentioned first wiring and secondwiring in the end direction of the substrate. With such routing wirings,etc., electrical connection to an external power source via connectorsor other such electronic parts mounted on the substrate can beestablished, for example. The pad electrodes are preferably formed widerthan the routing wirings.

With a drive substrate thus configured, matrix wiring can be formed in asingle-layer structure over a single-layer substrate. Thus, a pluralityof light emitting elements can be mounted at high density by varying thewidth, length, spacing, and so forth of the wiring as desired. Inparticular, since there is no need to form the so-called matrix wiringwith a multilayer structure, it can be thinner and smaller in size.Also, since the steps involved in manufacturing this drive substrate areextremely simple, not only does this help prevent an increase in themanufacturing cost, but shrinkage of the substrate can also be avoided,and a drive substrate of good precision can be obtained. Furthermore,because a single-layer structure is used, even though the light emittingelements are disposed at high density, the heat attributable to heatgeneration by the light emitting elements will not be trapped inside thesubstrate, and will instead be quickly released from the front and backsides of the substrate, so heat dissipation is even better.

Also, with this drive substrate, particularly because each second wiringis segmented by the first wiring, in that state the plurality of secondwiring are not electrically connected together. However, as will bediscussed below, in case where light emitting elements are mounted so asto bridge segmented second wirings, the segmented wirings can be linkedto each other. Thus, a plurality of second wirings that are electricallyconnected are disposed paired up with the first wiring. As a result, adrive substrate can be obtained in which a plurality of light emittingelements can be drive-controlled independently of each other.

Light Emitting Elements

Light emitting diodes are preferably used as the light emittingelements. The light emitting elements has, for example, a semiconductorstacked-layer structure including a first conduction layer, a lightemitting layer, and a second conduction layer, formed by any of varioussemiconductors such as InN, AlN, GaN, InGaN, AlGaN, InGaAlN, and othersuch nitride semiconductors, III-V-group compound semiconductors,II-VI-group compound semiconductors, and so forth, on a substrate, and afirst electrode and second electrode are also formed. Examples of thesubstrate of the light emitting elements include sapphire and other suchinsulating substrates, and SiC, silicon, GaN, GaAs, and other suchconductive substrates. However, ultimately, the light emitting elementsneed not have these substrates, and the substrate may be removed afterthe stacking of the semiconductor layer.

First Electrode and Second Electrode

The first electrode and the second electrode are connected to the firstconduction layer and the second conduction layer, respectively, butusually it is preferable if the first electrode is connected on thefirst conduction layer exposed by removal of part of the secondconduction layer and the light emitting layer stacked over the firstconduction layer, the second electrode is connected on a secondconduction-type semiconductor layer, and the first electrode and thesecond electrode are disposed on the same face side of the stacked-layerstructure. The first conduction layer is preferably n type, and thesecond conduction layer p type.

The first electrode and the second electrode are usually disposed on theinside of the light emitting elements in plan view. The position andsize of the first and second electrodes are preferably adjusted to aposition and size that afford reliable connection to the first wiringand the second wiring of the drive substrate.

For example, the first electrode is preferably disposed in the centerportion of the light emitting elements, and the second electrode isdisposed so as to surround the first electrode. The first wiringconnected to the first electrode is disposed sandwiching the segmentedsecond wiring, so the first electrode preferably has a width that is thesame as or less than that of the first wiring. A plurality of firstelectrodes may also be disposed on the surface of the second conductionlayer.

The second electrode usually has an overall electrode that coverssubstantially the entire surface of the second conduction layer in orderfor current to be uniformly diffused in-plane to the second conductionlayer, and a pad electrode whose upper surface is a connecting portionin order to connect to the second wiring and formed on the overallelectrode. The overall electrode is preferably an ohmic electrode thatcan make a good electrical connection to the second conduction layer.The overall electrode is usually formed over the entire surface of thesemiconductor stacked-layer structure other than the region where thefirst electrode is formed, so entire surface other than a portion wherethe pad electrode is formed is preferably covered by an insulatingprotective film or the like. There are preferably a plurality ofconnection portions, such as a first connection portion and a secondconnection portion, and there may be further one or more otherconnection portions. These connection portions are electrically linkedby the overall electrode. The width of the first connection portion andsecond connection portion of the second electrode preferably correspondsto the width of the second wiring. These portions may all have the samewidth or may have different widths.

Because the second electrode is thus connected to a plurality of secondwiring by mutually linked connection portions, the segmented secondwiring can be linked by the second electrode of the light emittingelements, so the wiring pattern can be made finer and matrix wiring bymeans of a simple pattern, that is, without using multilayer wiring of asubstrate wiring. In addition, current can be pass through the segmentedsecond wiring using the second electrode in addition to the inside ofthe semiconductor stacked-layer structure, so conductive resistance canbe lower when applying current. This allows the heat generated duringthe light emitting element lighting to reduce, as a result, thereliability of the light emitting device can be enhanced.

The second electrode may have a region that is opposite the first wiringin the mounting of the light emitting elements to the drive substrate.In this case, there may be a gap so that the second electrode and thefirst wiring are not in contact. Alternatively, as discussed above, aninsulating protective film may be formed on the surface of the firstwiring in the region opposite the second electrode or on the surface ofthe second electrode in the region opposite the first wiring. Thisreliably prevents short-circuiting.

Examples of the insulating protective film include oxides, nitrides, andfluorides of silicon, aluminum, niobium, zirconium, titanium, and thelike, either as a single-layer film or a multilayer film. The filmthickness can be adjusted as needed.

The first electrode and second electrode can be formed, for example,from aluminum, silver, gold, platinum, palladium, rhodium, nickel,tungsten, molybdenum, chromium, titanium, or another such metal or alloythereof, or ITO or another such oxide conductive material, either as asingle-layer film or a multilayer film. The film thickness can be anyone that is used in this field.

This overall electrode also functions as a reflective layer thatreflects the light emitted by the light emitting layer toward the lightextraction surface. Therefore, this overall electrode is preferablyformed so as to have good reflectivity for the wavelength of at leastthe light emitted by the light emitting layer. The overall electrode ispreferably, for example, a single-layer film composed of silver or asilver alloy with high optical reflectivity. The overall electrode mayalso be a multilayer film with a film composed of nickel and/or titaniumor the like, in which the above-mentioned silver or silver alloy film isthe lowermost layer.

When silver is used as the overall electrode, a cover electrode thatcovers the overall electrode is preferably provided. The cover electrodediffuses current over the entire surface of the second conduction layer,just as the overall electrode does. In addition, the cover electrodecovers the top and side surfaces of the overall electrode, shades theoverall electrode, and prevents contact between the overall electrodeand the second electrode. Consequently, the cover electrode functions asa barrier layer for preventing migration of the material of the overallelectrode, and particularly, silver. The cover electrode can be formed,for example, from one or more metals selected from the group consistingof titanium, gold, tungsten, aluminum, copper, and so forth, or an alloyof these. The cover electrode may be a single-layer film or a multilayerfilm. More specifically, the cover electrode may be a single-layer filmof an Al—Cu alloy, an Al—Cu—Si alloy, or the like, or a multilayer filmthat includes such a film. The overall electrode and the cover electrodecan each be formed by sputtering, vapor deposition, or the like.

The surfaces of the first electrode and the second electrode usually arenot level since the first electrode and the second electrode areconnected to different surfaces at different level within thesemiconductor layer. However, it is preferable in the case where thethickness of the first electrode and second electrode is controlled, ora bump electrode, a conductive single-layer film or stacked film, or thelike is disposed over the first electrode and the second electrode, sothat the two surfaces will be formed substantially flush, that is, sothat their surfaces are located at the same height. A configuration suchas this affords reliable mounting to the drive substrate of the lightemitting device, without short-circuiting.

The light emitting elements usually may be mounted face-up, in which theinsulated substrate side of the light emitting elements is bonded to thedrive substrate, but flip-chip mounting is preferable. In this mounting,it is preferable to use a bonding member selected from among a solderbased on tin-bismuth, tin-copper, tin-silver, gold-tin, or the like, aconductive paste of silver, gold, palladium, or the like, a bump(printed bump, stud bump, plated bump and the like), an anisotropicconductor, a low-melting point metal, or another such braze, or thelike, for example.

When the light emitting elements are flip-chip mounted, the firstelectrode and/or the second electrode is preferably connected to thefirst wiring and/or second wiring via a stud bump or a solder ball. Itis particularly favorable for the second electrode to be connected tothe second wiring via a stud bump. Since the second electrode functionsas a metal member that bridges the segmented second wiring, it isnecessary for it not to be electrically connected to the first wiring,but to be connected to the second wiring at two or more points.Accordingly, it is preferable for it to be connected by a member thatcan maintain a constant height, without spreading out, so as not to comeinto contact with the first wiring that is disposed so as to segment thesecond electrode. The stud bump referred to here means that there is awire (stud) of a specific length (height) on a compression ball that hasbeen press-fitted to an electrode. Usually, a stud bump can be formedwith a wire bonding apparatus or a bump bonding apparatus. The lightemitting elements that are thus connected preferably have theabove-mentioned bonding member interposed in order to strengthen thebonding between electrode and wiring.

A solder ball preferably has a core and a cover component on the outsideof the core, whose melting point is lower than the melting point of thecore. The core should be able to maintain its shape during reflowmounting with a solder ball. More specifically, it is preferable if themain component of the core is copper, and the cover component is made ofan alloy that contains gold and one or more of silicon, germanium, andtin. It is also favorable for there to be a specific under-layer thatsurrounds the core, and a tin-based cover film over this. Nickel, Ni—B,Ni—P, or the like can be used as the under-layer. The tin-based coverfilm here may be a single-layer cover film of a tin alloy, or may be amultilayer film of tin and other alloy components or a tin alloy. In thecase of a multilayer film of tin and other alloy components or a tinalloy, the tin and other alloy components or tin alloy are melted in thereflow step for forming a bump of a copper core ball over the wiring ofthe drive substrate, which forms a uniform alloy layer.

The core preferably has copper as its main component (that is, has acopper content of at least 50 wt %). It is particularly favorable to usea ball of an alloy of copper and one or more of zinc, tin, phosphorus,nickel, gold, molybdenum, and tungsten, or a ball with a copper contentof at least 99 wt %, because the thermal conductive and electricalconductivity will be superior.

For preventing to spread out the bonding member, as described above,part of the surface of the first wiring or the second wiring ispreferably remover by laser trimming, and an exposed surface of thefirst wiring or the second wiring thus obtained is preferably convertedto the oxide. This allows the bonding member to ensure the stability ofthe position and shape even when the bump or the like is used to bondthe wiring and the electrode.

With the light emitting device disclosed herein, the light emittingelements are mounted over the first wiring of the above-mentioned drivesubstrate, and over at least two of the second wiring (two or more whenthe second wiring is segmented) disposed apart from each other and oneither side of the first wiring. The first electrode of the lightemitting elements is connected on the first wiring, and the secondelectrode is connected on the second wiring. Two or more of the lightemitting elements are preferably disposed in the second direction, andeven more preferably two or more are disposed in each of the firstdirection and the second direction. Consequently, the first wiring andthe second wiring are electrically connected in a matrix, for example,in the first direction and the second direction, or in a row in thesecond direction, by the light emitting elements at locationscorresponding to the sites where they intersect. This allows the driveof the light emitting elements to be controlled independently. Thus,just the desired number and the light emitting elements at the desiredlocations can be switched on or off as desired. Also, the amount ofcurrent can be controlled for just the light emitting elements desired,and contrast can be provided within the light emitting device. Inparticular, as discussed above, when the second electrode of the lightemitting elements is connected to two or more of the segmented secondwiring, current can be pass through the segmented second wiring usingthe second electrode in addition to the inside of the semiconductorstacked-layer structure so conductive resistance can be lower duringcurrent applied.

And since a light emitting device can be obtained with which the turningon and off of light emitting elements can be controlled as desired, itcan be used effectively in an adaptive driving beam headlamp system aswhat is known as an adaptive driving beam headlamp, as will be discussedbelow.

Reflective Member

The light emitting elements mounted on the drive substrate preferablyeach have a reflective member formed around the light emitting element.The reflective members are preferably disposed in contact with the sidesurfaces of the light emitting elements. The reflective members arepreferably disposed surrounding the connection components of the firstelectrode and first wiring, and of the second electrode and secondwiring, between the substrate and the light emitting elements. Thereflective members may be disposed for each light emitting element, orfor a group of light emitting elements, but are preferably formedintegrally with respect to all of the light emitting elements. Thisallows all of the light emitted from the light emitting elements to beefficiently extracted from the light extraction surface side (the upperor lower surfaces of the light emitting elements). Also, this affords aclear brightness boundary between the emission region and thenon-emission region, giving an emission state that has bettervisibility.

The reflective material that makes up the reflective member ispreferably one capable of efficiently reflecting the light emitted fromthe light emitting elements, etc., and more preferably a materialcapable of reflecting at least 80%, and still more preferably at least90%, of the peak wavelength of this light. An insulating material ispreferable.

There are no particular restrictions on the reflective material, but amaterial capable of reflecting light is preferable, such as particles ofSiO₂, TiO₂, ZrO₂, BaSO₄, MgO, ZnO, and the like. These materials may beused singly, or a combination of two or more types may be used. Thesematerials are usually used as a mixture with a thermosetting resin, athermoplastic resin, or the like, specific examples of which includeepoxy resin compositions, silicone resin compositions, silicone-modifiedepoxy resins, and other such modified epoxy resin compositions;epoxy-modified silicone resins and other such modified silicone resincompositions; hybrid silicone resins; polyimide resin compositions andmodified polyimide resin compositions; polyphthalamide (PPA);polycarbonate resin; polyphenylene sulfide (PPS); liquid crystal polymer(LCP); ABS resin; phenol resin; acrylic resins; PBT resins, and othersuch resins.

The reflective member preferably has a thickness of about 1 to 100 μm,for example. It is particularly preferable when the upper surface of thereflective member does not cover the upper surfaces of the lightemitting elements, and is formed so as to be disposed eithersubstantially level with the upper surfaces of the light emittingelements, or above the upper surfaces of the light emitting elements.This prevents the light of the light emitting elements from leaking outin the lateral direction. Also, relatively strong light emitted from theside surfaces of the semiconductor layer including the light emittinglayer can be blocked by the reflective member, and color unevenness canbe reduced. Also, the above-mentioned reflective material is preferablycontained in an amount of at least 40 wt % with respect to the totalweight of the reflective member in order to improve reflectivity.

Wavelength Conversion Layer

A wavelength conversion layer converts the light from the light emittingelements to a different wavelength, and is preferably disposed in thelight emitting device on the light extraction surface side of the lightemitting elements. A phosphor or quantum dots can be used, for example,as the wavelength conversion layer.

Examples of the phosphor constituting a phosphor layer as one of thewavelength conversion layer include nitride-based phosphors oroxynitride-based phosphors activated mainly with lanthanoid elementssuch as europium or cerium, and sialon-based phosphors. Morespecifically,

(A) α or β-sialon phosphors or various alkaline earth metal nitridesilicate phosphors, which are activated with europium,

(B) alkaline earth metal halogen apatite phosphors, alkaline earthhalo-silicate phosphors, alkaline earth metal silicate phosphors,alkaline earth metal borate halogen phosphors, an alkaline earth metalaluminate phosphors, alkaline earth metal silicates phosphors, alkalineearth metal sulfides phosphors, alkaline earth metal thiogallatephosphors, alkaline earth metal nitride silicate phosphors, germanatesalt phosphors, which are activated with lanthanoid such as europium ortransition metal such as manganese,

(C) rare earth aluminates phosphors, rare earth silicates phosphors,which are activated with lanthanoid elements such as cerium, or

(D) organic substance and organic complexes which are activated withlanthanoid element such as europium.

Examples of the quantum dot include a nano-size high-dispersiveparticles of semiconductor materials, for example group II-VI, groupIII-V and group IV-VI semiconductors, more specifically CdSe, core-shelltype CdS_(x)Se_(1-x)/ZnS, GaP, InP, and GaAs. Further, InP, InAs, InAsP,InGaP, ZnTe, ZnSeTe, ZnSnP and ZnSnP₂ are included in the examples.

The phosphor layer is usually disposed on the upper surfaces of thelight emitting elements, around the time when the light emittingelements are mounted on the drive substrate, in substantially the samesize and shape as those of the light emitting elements, or slightlylarger.

The phosphor layer can be formed by adhesive bonding, electrodeposition,electrostatic coating, sputtering, vapor deposition, potting, printing,spraying, or another such method. Adhesive bonding allows the phosphorlayer to be formed simply, by affixing a sheet or plate that uniformlyincludes the phosphor layer. Electrodeposition, electrostatic coating,sputtering, and vapor deposition allow the phosphor layer to be affixedwithout the use of a binder, over the entire substrate and lightemitting elements. After the phosphor layer has been affixed, it may beimpregnated with a resin or the like that will serve as a binder. Thephosphor can be selectively affixed by using a phosphor dispersed in alight-transmissive member in potting, printing, or spraying. Thelight-transmissive member here can be formed from a material capable oftransmitting at least 60%, and preferably at least 70%, and morepreferably at least 80%, of the peak wavelength of the light emittingelements, and can be selected as needed from among the above-mentionedthermoplastic resins, thermosetting resins, and so forth.

The thickness of the phosphor layer can be suitably adjusted accordingto its manufacturing method, such as the phosphor particle depositionconditions and duration. For instance, about 0.01 to 100 μm ispreferable. The phosphor layer is preferably formed in a substantiallyuniform thickness.

When the reflective member is formed as discussed above, it preferablyalso covers the side surfaces of the phosphor layer, just as it does theside surfaces of the light emitting elements. This allows the light oflit light emitting elements to be reliably extracted from the lightextraction surfaces, regardless of whether adjacent light emittingelements are turning on and off. Preferably the entire side surfaces ofthe phosphor layer are covered by the reflective member, both in thethickness direction and around the outside. This allows theabove-mentioned effects to be obtained more efficiently.

Connectors or other such electronic parts or the like may be furthermounted corresponding to the layout of the above-mentioned routingwirings and so forth. A protective element may also be mounted.

Adaptive Driving Beam Headlamp System

With an adaptive driving beam headlamp system, while a vehicle is beingdriven with its headlamps on high beam, in the case where there is avehicle ahead (such as a vehicle in an oncoming lane or a vehicle aheadin the same lane) or a pedestrian appears in front of the vehicle, anonboard camera detects the position of the car or pedestrian ahead, dimsthe light at only that location, and keeps the high beams shining on theother locations. The shaded area is automatically adjusted out of thearea illuminated by the headlights, so as to match the position of thevehicle or person ahead, which keeps the driver of the vehicle ahead orthe pedestrian from being blinded by the light. On the other hand, thedriver of the vehicle will always have a field of vision that is closeto that of driving with the high beams on, so the driver can easily seepedestrians, road signage, the shape of the road in the distance, and soforth, and this results in safer operation.

This system has the above-mentioned light emitting device, an onboardcamera that recognizes the position of a vehicle or person ahead, etc.,and an electronic control unit that determines the area to be shaded andthe light distribution pattern. With this configuration, the lightemitting device takes on the role of an adaptive driving beam headlampwith which control to either shade or illuminate a certain position isachieved by turning on and off the individual light emitting elementsunder the relational action of the onboard camera, the electroniccontrol unit, etc.

Therefore, a drive unit (ACT) for lens movement or lamp swivel or thelike, which was required with a conventional automotive forwardillumination apparatus, is not needed, and the same control is possiblewith just the turning on and off of the light emitting elements.

The light emitting device usually functions as a pair of automotiveadaptive driving beam headlamps disposed on the left and right sides ofthe vehicle. As discussed above, each light emitting device is equippedwith a plurality of light emitting elements. In addition to these lightemitting elements, the light emitting device may also has a projectinglens, a reflecting mirror, lamp bodies to house these, and so on.

The onboard camera captures images of what is ahead of the vehicle andtransmits the results to the electronic control unit.

The electronic control unit is usually constituted by a microprocessorthat includes a CPU, a RAM, a ROM, and/or an I/O, etc. Programs forperforming light distribution control and so forth are stored in theROM. The RAM is used as a work area when the CPU performs various kindsof computation, etc.

The electronic control unit is connected to the onboard camera, detectsvehicles ahead (oncoming vehicles, vehicles ahead in the same lane,pedestrians) as well as other objects on the road, pavement markings,and the like, and calculates the data needed for light distributioncontrol, such as the attributes, positions, and so forth of thesethings. The electronic control unit determines the light distributionpattern that suits the driving situation on the basis of the calculateddata.

The electronic control unit then determines the amount of control of thelight emitting device required to achieve this light distributionpattern. The amount of control here is, for instance, the position,range, etc., of the shaded region, and control details for the variouslight emitting elements in the light emitting device (whether they areon or off, whether the power is on, etc.) are determined on the basis ofthis control amount.

The electronic control unit is usually connected to the light emittingdevices via a driver. Thus, the determined control details are sent bythe driver to the light emitting devices, and the specific on/offswitching of the light emitting elements in the light emitting device iscontrolled.

Embodiments of the drive substrate, light emitting device, and adaptivedriving beam headlamp system disclosed herein will now be described inspecific terms through reference to the drawings.

Embodiment 1 Drive Substrate

As shown in FIG. 1A, a drive substrate 10 used by a light emittingdevice 90 in this embodiment has a substrate 13, first wiring 11(examples of first wiring members), and second wiring 12 (examples ofsecond wiring members).

The substrate 13 is constituted by a single-layer structure made ofaluminum nitride. Its size is 10×10 mm and its thickness is 0.5 mm, forexample.

The first wiring 11 and the second wiring 12 are formed by aTiW/Cu/Ni/Au stacked-layer structure (starting from the substrate 13side) on a first main surface 13 a of the substrate 13. The TiW andcopper films are each formed in a thickness of 0.1 μm by sputteringthrough a mask on the substrate 13, and the nickel and gold films areformed on the surface thereof by plating in a thickness of 1.27 μm and1.5 μm, respectively.

When the first main surface 13 a of the substrate 13 will be the xyplane, for example, there are four first wiring 11 disposed extending inthe x axis direction (as the first direction), as shown by the arrow.For example, the width Q of the first wiring 11 is 100 μm, and thelength is 3 mm. The spacing between adjacent first wiring 11 is 500 μm.

The second wiring 12 are disposed in a number corresponding to four, topair up with the four first wiring 11, along the y axis direction (asthe second direction), as shown by the arrow. The second wiring 12disposed along the y axis direction are disposed separated from oneanother. Also, a single second wiring 12 branches in two at the otherend side. Thus, two second wiring 12 are disposed adjacent on the distalend side of the first wiring 11 and between the first wiring 11. Thewidth M of the second wiring 12 is 540 μm, the width N1 and N2 of onebranch of the second wiring 12 is 220 μm, the spacing between branched,adjacent second wiring 12 is 100 μm, and the length thereof is 480 μm.

Thus, the second wiring 12 are segmented by the first wiring 11, and inthe state of the drive substrate 10, the second wiring 12 are notelectrically connected to each other. However, the segmented secondwiring 12 are linked by mounting light emitting elements (discussedbelow), and consequently a plurality of electrically connected secondwiring 12 (four here) are disposed so as to be paired with the firstwiring 11. The result is a drive substrate that allows the drive of aplurality of light emitting elements to be controlled independently fromone another.

The first wiring 11 and the second wiring 12 are respectively connectedto routing wiring 11 a and 12 a at the other end side (different formthe distal end), and the routing wiring 11 a and 12 a extend toconnector-use pad electrodes 11 b and 12 b disposed at the end of thedrive substrate 10.

The drive substrate 10 thus configured allows matrix wiring to be formedin a single-layer structure on the single-layer substrate 13, so aplurality of light emitting elements can be mounted at high density byvarying the width, length, spacing, and so forth of the wiring asneeded. In particular, since there is no need to form the matrix wiringfrom a multilayer structure, the thickness or size thereof can be keptsmall. Also, using a single-layer structure means that even though thelight emitting elements are disposed at high density, heat attributableto the emission of the light emitting elements will not be trappedinside the substrate, and can be quickly released from the front andrear surfaces, so heat dissipation can be made even better.

Because the steps involved in manufacturing this drive substrate areextremely simple, increases to the manufacturing cost can be kept low.Furthermore, expansion and contraction of the substrate and so forth canbe avoided, so that a more accurate drive substrate is obtained.

Light Emitting Device

As shown in FIGS. 2C and 2D, the light emitting device 90 in thisembodiment is configured such that sixteen light emitting elements 14are mounted as shown in FIG. 1B on the above-mentioned drive substrate10.

As shown in FIGS. 1D, 1E, and 1F, for example, each light emittingelement 14 has a semiconductor stacked-layer structure SC that includesa first conduction layer, a light emitting layer, and a secondconduction layer on a sapphire substrate S, and a first electrode 15 andsecond electrodes 16 are formed on the same face side of thissemiconductor stacked-layer structure SC.

As shown in FIG. 1C, the first electrode 15 and the second electrodes 16are disposed on the inside of the light emitting element 14 in planview. The first electrode 15 has a circular shape with a diameter ofabout one-fourth to one-third one side of the light emitting element 14,for example, and is disposed in the center of the light emitting element14. The second electrodes 16 are disposed so as to surround the firstelectrode 15, in an outer shape that is about the same as or slightlysmaller than the light emitting element 14.

The first electrode 15 and the second electrodes 16 have differentsurface positions on the connected semiconductor layer, so the surfaceof the semiconductor layer on which these electrodes are formed isstepped at the outset. However, the surfaces of the first electrode 15and the second electrodes 16 can be formed substantially flush, that is,formed so that they are located at the same height, by controlling thethickness of the conductive single-layer film or stacked film, such asan external connection-use electrode connected to the first electrodeand the second electrodes, or the thickness of the first electrode andthe second electrodes.

When such light emitting elements 14 are mounted on the drive substrate10, the light emitting elements 14 are flip-chip mounted. The firstelectrode 15 in this embodiment is connected to the first wiring 11 viaa stud bump whose material is gold, and the second electrodes 16 areconnected to the second wiring 12 via stud bumps whose material is gold.

In the case where the second electrodes 16 and the second wiring 12 areconnected by AuSn or other such solder material as a bonding member, forexample, instead of using stud bumps, the solder material will spreadout along the shape of the second electrodes 16. As shown in FIGS. 1Band 1C, part of the first wiring 11 is opposite the second electrodes 16of the light emitting elements 14. Accordingly, when the bonding membersuch as this is used, short-circuiting between the first wiring 11 andthe second electrodes can be prevented by forming a protective filmcomposed of SiO₂, for example, in the region opposite the secondelectrodes 16 of the first wiring 11. When a member other than solder isused as the bonding member, i.e., the bump is used as described above,the protective film is also preferably formed in the region opposite thesecond electrodes 16 of the first wiring 11.

More specifically, as shown in FIGS. 1D to 1F, a protective film 19 ispreferably formed on the surface of the second electrodes 16 so as toexpose at least two connection parts or connection components 16 a and16 b (for example, four connection components 16 a, 16 b, 16 c, and 16d), and also to expose the first electrode 15.

The light emitting element 14 is fixed by a bonding member such that thefirst electrode 15 disposed in the center is disposed in the center inthe x axis direction of two of the second wiring 12 disposed apart fromeach other on either side of the first wiring 11 (when branched, thentwo on each side). Also, it is fixed by a bonding member such that bothsides of the second electrodes 16 disposed surrounding the firstelectrode 15 are each disposed on two of the second wiring 12.Consequently, the second wiring 12 are electrically connected in the ydirection by the light emitting element 14 at mutually isolated sites,without intersecting.

Accordingly, the drive of each of the light emitting elements can beindependently controlled. As a result, just the light emitting elementsat the desired positions can be switched on or off in the desirednumber. Also, the amount of current can be controlled for just the lightemitting elements desired, and contrast can be provided within the lightemitting device.

In addition, by the second electrodes 16 are connected to the secondwiring 12 that are segmented by the plurality of connection components16 a to 16 d, current can be pass through the segmented second wiringusing the second electrode, so conductive resistance can be lower whenapplying current.

A phosphor layer is provided as a wavelength conversion layer 17 to eachof the light emitting elements 14, on the surface opposite the drivesubstrate 10. The wavelength conversion layers 17 have substantially thesame size and shape as the light emitting elements 14. The wavelengthconversion layers 17 are formed from glass containing YAG, are uniformin thickness over the entire surface, and are 100 μm thick.

A reflective member 18 is integrally formed on the drive substrate 10 onwhich the sixteen light emitting elements 14 are mounted such that thereflective member 18 is in contact with the entire side surfaces of thelight emitting elements 14, and is disposed between the light emittingelements 14 and the drive substrate 10.

The reflective member 18 is formed from a silicone resin containing 30wt % TiO₂. The size of the reflective member 18 is 2.5×2.5 mm, and itsthickness is about 0.25 mm.

The reflective member 18 also covers all of the side surfaces of thewavelength conversion layers 17, and its upper surface coincides withthe upper surfaces of the wavelength conversion layers. Consequently,the light of lit light emitting elements can be reliably extracted fromthe light extraction surface, regardless of the turning on and off ofadjacent light emitting elements.

As shown in FIG. 1G, the light emitting device 90 configured as abovehas a circuit in which a matrix circuit is completed by the mounting ofthe light emitting elements, so the turning on and off of the desiredlight emitting elements can be freely controlled in the desired number.

The above-mentioned light emitting device can be manufactured asfollows.

First, as shown in FIG. 2A, the drive substrate 10 and the lightemitting elements 14 are prepared. The light emitting elements 14 aremounted via stud bumps in a 4×4 matrix. The spacing between the lightemitting elements 14 is 100 μm, for example.

Then, as shown in FIG. 2B, the wavelength conversion layers 17 areplaced over the light emitting elements 14. The wavelength conversionlayers 17 can be fixed to the light emitting elements 14 with alight-transmissive adhesive agent, for example.

After this, as shown in FIG. 2C, the 16 light emitting elements 14 areintegrally covered by the reflective member 18. The reflective member 18is formed by molding in upper and lower molds, for example. The entireside surfaces of the light emitting elements 14 and between the lightemitting elements 14 and the substrate 13 are covered by the reflectivemember 18, and the upper surface of the reflective member 18 is flushwith the upper surface of the wavelength conversion layers.

Modification Example 1: Drive Substrate

As shown in FIG. 3A, the drive substrate 20 in this modification examplehas the substrate 13, first wiring 21, and second wiring 22. The firstwiring 21 and the second wiring 22 are disposed extending in the x axisdirection and the y axis direction, respectively, so that the lightemitting elements are disposed in a 3×3 matrix.

The first wiring 21 is disposed extending in three parallel rows in thex axis direction, as indicated by the first wiring 21 x, 21 y, and 21 z.

The second wiring 22 is disposed in a number corresponding to three rowsso as to pair up with the three rows of first wiring 21 along the y axisdirection, as indicated by the second wiring 22 x, 22 y, and 22 z.However, the second wiring 22 x, 22 y, and 22 z disposed along the yaxis direction are disposed with two between the first wirings 21, oneat the distal end of the first wiring 21, and one at the other end, withthe four of them separated from one another.

The width M of the second wiring 22 is 540 μm, and the length is 480 μm.The width Q of the first wiring 21 is 100 μm.

Otherwise, the configuration is substantially the same as that of thedrive substrate in Embodiment 1.

As shown in FIG. 3B, the light emitting elements 14 are fixed by bondingmembers on the drive substrate 20 so that the first electrode disposedin the center is disposed in the center in the x axis direction of thetwo second wiring 22 disposed apart from each other on either side ofthe first wiring 21. Also, they are fixed by bonding members so thatboth sides of the second electrodes disposed surrounding the firstelectrode are each disposed on two of the second wiring 22.

Consequently, the first wiring 21 and the second wiring 22 areelectrically connected to each other in a low-resistance state in the xdirection and the y direction by the light emitting elements 14 at siteswhere they intersect, but are separated from one another. Thus, theeffect is substantially the same as that of the drive substrate inEmbodiment 1.

Embodiment 2 Drive Substrate

As shown in FIG. 4A, the drive substrate 30 in this embodiment has thesubstrate 13, first wiring 31, and second wiring 32. The first wiring 31and the second wiring 32 are disposed in the x axis direction and the yaxis direction, respectively, so that the light emitting elements aredisposed in a 3×3 matrix.

The first wiring 31 is disposed extending in three rows in the x axisdirection.

However, one row of the first wiring 31 is branched into three.

The second wiring 32 is disposed in a number corresponding to three rowsso as to pair up with the three rows of first wiring 31 along the y axisdirection, as indicated by the second wiring 32 x, 32 y, and 32 z.However, the second wiring 32 x, 32 y, and 32 z disposed along the yaxis direction are disposed with two between the first wirings 31, oneat the distal end of the first wiring 31, and one at the other end, withthe four of them separated from one another.

Otherwise, the configuration is substantially the same as that of thedrive substrate in Embodiment 1.

Light Emitting Elements

With the light emitting device in this embodiment, as shown in FIG. 4C,the light emitting elements 24 are such that a semiconductorstacked-layer structure SC including a first conduction layer, a lightemitting layer, and a second conduction layer is stacked over a sapphiresubstrate S, and first electrodes 15 and second electrodes 16 are formedon the same face side as this semiconductor stacked-layer structure SC.

Three of the first electrodes 15 are disposed parallel to each other onthe inside of the light emitting elements 24 in plan view, so as tocorrespond to the pattern of the first wiring of the drive substratediscussed above. The width of the first electrodes 15 is about 70 μm,and the length is about 420 μm. Four of the second electrodes 16 aredisposed above and below, and parallel to, the first electrodes 15, asthe connection components 16 a to 16 g.

Otherwise, the configuration is substantially the same as that of thelight emitting device in Embodiment 1.

As shown in FIG. 4B, the light emitting element 14 is fixed by a bondingmember on this drive substrate 30 so that the first electrodes disposedin the center will be disposed in the center in the x axis direction oftwo of the second wiring 32 disposed apart from each other on eitherside of the first electrode 31. It is also fixed by a bonding member sothat both sides of the second electrodes disposed surrounding the firstelectrodes are each disposed on two of the second wiring 32.

Consequently, the first wiring 31 and the second wiring 32 areelectrically connected to each other in a low-resistance state in the xaxis direction and the y axis direction by the light emitting elements14 at sites where the wiring does not intersect, and is separated fromone another. Thus, the effect is substantially the same as that of thedrive substrate in Embodiment 1.

Modification Example 2: Drive Substrate

As shown in FIG. 5A, the drive substrate 40 in this modification examplehas the substrate 13, first wiring 41, and second wiring 42. The firstwiring 41 and the second wiring 42 are disposed in the x axis direction(stepped) and the y axis direction, respectively, so as to dispose thelight emitting elements in a 3×3 matrix.

The first wiring 41 is disposed extending in three stepped rows in the xaxis direction. The second wiring 42 is disposed in the y axis directionin a number corresponding to three rows so as to pair up with the threerows of the first wiring 41, as indicated by the second wiring 42 x, 42y, and 42 z. However, two rows of the second wiring 42 disposed in the yaxis direction are disposed between the first wiring 41, one is disposedat the distal end of the first wiring 41, and one at the other end, withthe four of them separated from one another. Three of the rows of thesecond wiring 42 are offset in the y axis direction according to thesteps of the first wiring 41. Otherwise, the configuration issubstantially the same as that of the drive substrate in Embodiment 1.

As shown in FIG. 5B, the light emitting elements 14 are fixed by bondingmembers on the drive substrate 40 so that the first electrode disposedin the center is disposed in the center in the x axis direction of thetwo second wiring 42 disposed apart from each other on either side ofthe first wiring 41. Also, they are fixed by bonding members so thatboth sides of the second electrodes disposed surrounding the firstelectrodes are each disposed on two of the second wiring 22.

Consequently, the first wiring 41 and the second wiring 42 areelectrically connected to each other in a low-resistance state in the xdirection and the y direction by the light emitting elements 14 at siteswhere they are separated from one another, without intersecting. Thus,the effect is substantially the same as that of the drive substrate inEmbodiment 1.

Adaptive Driving Beam Headlamp System

As shown in FIG. 6A, the adaptive driving beam headlamp system 50 inthis embodiment has the light emitting device of Embodiment 2 asadaptive driving beam headlamps 51, and further has an onboard camera 52that recognizes the position of a vehicle ahead, and an electroniccontrol unit 54 that determines the light distribution pattern and thearea to be shaded.

The light emitting devices function as a pair of automotive adaptivedriving beam headlamps 51 that are disposed on the left and right of avehicle. The light emitting devices are equipped with light emittingelements, as well as a projecting lens and a lamp body to house these.

The onboard camera 52 captures images of what is ahead of the vehicleand transmits the results to the electronic control unit 54 via a driver53.

The electronic control unit 54 is usually constituted by amicroprocessor that includes a CPU, a RAM, a ROM, and/or an I/O, etc.Programs for performing light distribution control and so forth arestored in the ROM. The RAM is used as a work area when the CPU performsvarious kinds of computation, etc.

Control Flow

The adaptive driving beam headlamp system 50 thus configured can performcontrol as shown in FIG. 6B.

First, the onboard camera 52 acquires the necessary data from in frontof the vehicle (S10). This data is an image of ahead of the vehicle, thevehicle speed, the distance between vehicles, the shape of the road, thelight distribution pattern, and so forth, for example. The acquired datais sent to the electronic control unit 54.

The electronic control unit 54 performs data processing on the basis ofthe acquired data (S20). This data processing results in the computationof attributes of an object ahead of the vehicle (a signal light, streetlamps, etc.), attributes of vehicles and so forth (oncoming vehicle,vehicle ahead, pedestrian), vehicle speed, the distance betweenvehicles, the brightness of an object, the road shape (lane width,straight road), and so forth.

Next, the electronic control unit 54 determines the proper lightdistribution pattern on the basis of the computed data (S30). Theselected control light distribution pattern is, for example, a high-beamlight distribution pattern, a focused light distribution pattern forwhen the vehicle speed is high, a diffused light distribution patternfor when the vehicle speed is low, a low-beam light distribution patternfor when an oncoming vehicle is detected, etc.

The electronic control unit 54 determines control amounts for whether toswitch on or off the various light emitting elements in the adaptivedriving beam headlamp 51, and whether the power is on (S40).

The electronic control unit 54 converts the determined control amountsinto driver data, and controls the drive of the adaptive driving beamheadlamp 51 through the driver 53 (S50). That is, the desired number oflight emitting elements, in the desired locations in the adaptivedriving beam headlamp 51, are individually switched on or off to realizethe desired light distribution pattern.

This series of flow steps is repeated at specific time intervals.

With the adaptive driving beam headlamp system in this embodiment, whilea vehicle is being driven with its headlamps on high beam, if there is avehicle ahead (such as a vehicle in an oncoming lane or a vehicle aheadin the same lane) or if a pedestrian appears in front of the vehicle, anonboard camera detects the position of the car or pedestrian ahead, dimsthe light at only that location, and keeps the high beams shining on theother locations. That is, the shaded area is automatically adjusted outof the area illuminated by the headlights, so as to match the positionof the vehicle or person ahead, which keeps the driver of the vehicleahead or the pedestrian from being blinded by the light. On the otherhand, the driver of the vehicle will always have a field of vision thatis, close to that of driving with the high beams on, so he can easilysee pedestrians, road signage, the shape of the road in the distance,and so forth, and this results in safer operation.

The drive substrate disclosed herein can be used for the mounting ofvarious kinds of electrical elements, such as semiconductor elements,light emitting elements, and the like. Also, the light emitting devicein which this substrate is used to operate, turning on and off, andotherwise control individual light emitting elements. This lightemitting device can be used in an adaptive driving beam headlamp systemwith which the light distribution pattern and the area to the shaded canbe controlled in light emitting element units.

It is to be understood that although the present invention has beendescribed with regard to preferred embodiments thereof, various otherembodiments and variants may occur to those skilled in the art, whichare within the scope and spirit of the invention, and such otherembodiments and variants are intended to be covered by the followingclaims.

What is claimed is:
 1. A light emitting device comprising: a substrate having a first main surface; a plurality of first wiring members that are formed on the first main surface, each of the first wiring members extending in a stepped shape along a first direction, the stepped shape being defined by a first portion extending in the first direction, a second portion continuously extending from the first portion in a direction intersecting with the first direction, and a third portion continuously extending from the second portion in the first direction; a plurality of second wiring members that are formed on the first main surface and extend in a second direction, each of the second wiring members being segmented into a plurality of second wiring portions; and a plurality of light emitting elements disposed along the second direction, each of the light emitting elements including a first electrode, a second electrode, and a semiconductor stacked-layer structure, with the first electrode and the second electrode being disposed on the same face side of the semiconductor stacked-layer structure, the first electrode being connected to a corresponding one of the first wiring members, the second electrode having a first connection part and a second connection part that is linked to the first connection part, and the first connection part and the second connection part being connected to a corresponding one of the second wiring members and bridging at least two of the segmented second wiring portions in the second direction.
 2. The light emitting device according to claim 1, wherein the first electrode is connected to the corresponding one of the first wiring members via a stud bump or a solder ball, or the second electrode is connected to the corresponding one of the second wiring members via the stud bump or the solder ball.
 3. The light emitting device according to claim 1, wherein the second electrode surrounds the first electrode, and surfaces of the first electrode and the second electrode are located at the same height.
 4. The light emitting device according to claim 1, wherein each of the first wiring members has a region that faces the second electrode, and an insulating protective film is formed on a surface of each of the first wiring members in the region or on a surface of the second electrode in the region.
 5. The light emitting device according to claim 1, further comprising a reflective member in contact with side surfaces of the light emitting elements.
 6. The light emitting device according to claim 1, wherein the plurality of light emitting elements is drive-controlled independently of each other.
 7. The light emitting device according to claim 1, wherein the first wiring members and the second wiring members are made of the same metal material.
 8. The light emitting device according to claim 1, wherein the substrate is a ceramic substrate with a single-layer structure.
 9. The light emitting device according to claim 1, wherein the first wiring members and the second wiring members are arranged in a regular pattern in column and row directions.
 10. The light emitting device according to claim 1, wherein at least one of the second wiring members is wider than at least one of the first wiring members.
 11. An adaptive driving beam headlamp system comprising: the light emitting device according to claim 1; an on-board camera configured and arranged to recognize a position of a vehicle ahead; and an electronic control unit configured to determine a light distribution pattern and an area to be shaded.
 12. The light emitting device according to claim 1, wherein the semiconductor stacked-layer structure includes a first conduction layer, a light emitting layer and a second conduction layer, the first electrode is further connected to the first conduction layer, the second electrode is connected on the second conduction layer in an portion in which the first conduction layer, the light emitting layer, and the second conduction layer are stacked in order of the first conduction layer, the light emitting layer and the second conduction layer, and the first connection part and the second connection part are linked via electrode material.
 13. A light emitting device comprising: a substrate having a first main surface; a plurality of first wiring members that are formed on the first main surface, each of the first wiring members extending in a stepped shape along a first direction, and being in contact with the first main surface of the substrate at least at a portion having the stepped shape; a plurality of second wiring members that are formed on the first main surface and extend in a second direction, each of the second wiring members being segmented into a plurality of second wiring portions; and a plurality of light emitting elements disposed along the second direction, each of the light emitting elements including a first electrode, a second electrode, and a semiconductor stacked-layer structure, with the first electrode and the second electrode being disposed on the same face side of the semiconductor stacked-layer structure, the first electrode being connected to a corresponding one of the first wiring members, the second electrode having a first connection part and a second connection part that is linked to the first connection part, and the first connection part and the second connection part being connected to a corresponding one of the second wiring members and bridging at least two of the segmented second wiring portions in the second direction.
 14. A light emitting device comprising: a substrate having a first main surface; a plurality of first wiring members that are formed on the first main surface, each of the first wiring members extending in a stepped shape along a first direction, and being thinner in a portion having the stepped shape than in other portion; a plurality of second wiring members that are formed on the first main surface and extend in a second direction, each of the second wiring members being segmented into a plurality of second wiring portions; and a plurality of light emitting elements disposed along the second direction, each of the light emitting elements including a first electrode, a second electrode, and a semiconductor stacked-layer structure, with the first electrode and the second electrode being disposed on the same face side of the semiconductor stacked-layer structure, the first electrode being connected to a corresponding one of the first wiring members, the second electrode having a first connection part and a second connection part that is linked to the first connection part, and the first connection part and the second connection part being connected to a corresponding one of the second wiring members and bridging at least two of the segmented second wiring portions in the second direction. 